Forest Pathology最新文献

Eucalyptus production mainly destined to cellulose pulp production has expanded strongly in the last 30 years in Uruguay. Eucalyptus smithii has recently emerged as a promising species for cellulose pulp production. However, an average of 40% of young trees die during the first and second summer of post-planting. In this study, 32 Phytophthora isolates were obtained from 132 E. smithii young trees with root and collar rot symptoms, confirming the association of Phytophthora to E. smithii decline. Based on phylogenetic analysis of ITS, TUB2, cox1 and HSP90 gene regions and phenotypical characteristics, two species belonging to the genera Phytophthora clade 4 were identified, P. alticola (96%) and P. boodjera (4%). Tested isolates of both species significantly reduced both shoot and root dry weights of inoculated E. smithii seedlings compared to control plants. To our best knowledge, this is the first time that P. alticola and P. boodjera are recovered from young symptomatic E. smithii trees in commercial plantations as well as the first time these species are found in the Americas.

Ocean Expo Park, established in 1976 on subtropical Okinawa Island, Japan, has approximately 8000 planted or naturally grown trees in an area of 77.2 ha. Windfall of these trees occurs mainly due to typhoons; wood chips made from the trunks and roots of windfall trees are commonly used as mulching material throughout the park areas, despite possible infection by pathogenic fungi such as Phellinus noxius, the pathogen causing brown root rot. P. noxius is distributed in tropical and subtropical areas worldwide and has a broad host range. The fungus can infect host plants with mycelia via root-to-root contact or with basidiospores. Here, we report the current status of tree damage caused by brown root rot in the park and infer the infection routes of P. noxius based on microsatellite markers. Among a total of 294 trees surveyed in the park, P. noxius was isolated from 13 trees of five species. P. noxius was observed more frequently on Ficus microcarpa than on other tree species. Ficus superba var. japonica was identified as a new host species, and Bombax ceiba was first recorded as a host plant of P. noxius in Japan. Among the 13 P. noxius isolates from the diseased trees, 2 isolates from adjacent diseased trees were considered to be of the same genet, while the other 11 isolates were different genets, indicating that infection by basidiospores occurred frequently among trees in the entire park, although spread via root systems also occurred between at least two adjacent trees. An identical genet was not detected at distant locations, which suggests that the disease does not spread via chips. However, mulching with chips can lead to wood decay due to decaying fungi other than P. noxius. Therefore, in accordance with the precautionary principle, the park currently prohibits the chipping and mulching of windfall or damaged trees and is considering disposal methods such as burning.

Cycas revoluta (Cycadaceae) is commonly cultivated as an ornamental tree in several countries. In April 2015, C. revoluta leaves showing brownish spots with a yellow halo that progressed to leaflet necrosis were observed in Belém, Pará state, Brazil. This study aimed to determine the aetiology of this disease on sago palm in Brazil. Based on DNA sequence-based phylogeny, morphology, and colony characterization, the fungus was identified as Pseudopestalotiopsis elaeidis. To the best of our knowledge, this is the first report of P. elaeidis associated with leaf spots on C. revoluta worldwide.

An outbreak of a new and severe disease was observed in Eucalyptus plantations of Bahia state, Brazil. An Ascomycota fungus has been frequently associated with the main symptoms of the disease namely leaf spot, branch cankers, shoot blight, defoliation, and dieback. Based on morphological characteristics, phylogenetic analysis (ITS and TEF-1α genes), and pathogenicity test on Eucalyptus plants, Pseudoplagiostoma eucalypti was identified as the causal agent of the disease. Although P. eucalytpi has been known from in Brazil since 1998, this is the first report of it causing severe disease and die-back on Eucalyptus spp. and we also record new symptoms associated with the pathogen.

Fungi of the Cryphonectriaceae family are globally known to be tree pathogens. In Brazil, several species of Chrysoporthe have been found causing stem and branch cankers in Pleroma (= Tibouchina) spp. Recently, Chrysoporthe puriensis was described as a new species causing stem and branch cankers in Pleroma granulosum, Pleroma candolleanum, and Pleroma heteromallum, all native species of the Melastomataceae family. During an investigation to collect isolates of the Cryphonectriaceae family in an important Brazilian biome, the Atlantic Forest, in Serra do Mar, structures typical of Chrysoporthe species were found in a different host, Pleroma mutabile. Fruiting bodies present in the bark of these trees were collected and isolated. The isolates were submitted on morphological characterization and phylogenetic analyses of the internal transcribed spacer (ITS) and β-tubulin gene regions using Maximum likelihood, Bayesian inference and Maximum parsimony methods. The isolates collected, for this study, were identified as C. puriensis. Pathogenicity tests on seedlings of Pleroma species and Eucalyptus clones revealed C. puriensis can infect and cause canker in these plant species as mortality. The results demonstrate the importance of delimiting the C. puriensis collection range to track its dissemination in other hosts. No host specificity was observed in the inoculation tests, suggesting this is an important finding, the pathogen causes diseases and mortality in several plants of the Atlantic Forest. Additionally, the pathogen can affect others hosts, such as Eucalyptus clones in commercial plantations.

In this study, the effect of pine mistletoe (Viscum album subsp. austriacum) on basal area increment of Crimean pine and Scots pine was investigated. Dendrochronological data were collected from 223 (71 uninfected and 152 infected) Crimean pines and 195 (77 uninfected and 118 infected) Scots pines located in Kastamonu province of Turkey in 2014. Infected sample trees were classified as light, moderate or severe infection levels. Growth trends and basal area increment loses were compared between uninfected and infected trees for the periods of the last 10, 20 and 30 years. In addition, infection status of forest stands was investigated using temporary sample plots; 27 plots in Crimean pine stands and 26 plots in Scots pine. Results demonstrated that basal area increments were negatively affected by pine mistletoe for both species. Mean basal area increment losses of infected trees for the last decade were determined as 24% for Scots pine and 26% for Crimean pine. Basal area increment losses varied by infection levels (light, moderate and severe) as follows: 25%, 20% and 28% for Scots pines and 20%, 32% and 9% for Crimean pines. Scots pine stands were more severely infected by pine mistletoe than Crimean pine stands. There were negative correlations between number of infected trees and stand density for both species, while positive correlation was detected between the number of infected trees and mean diameter for Scots pine. The results of this study indicate that the pine mistletoe infection has negative effect on radial growth of Scots pine and Crimean pine trees. The results can be an important contribution to the forest management and protection activities in mistletoe-infected stands.

Serpula himantioides is a widely distributed saprotrophic fungus that causes root and butt rot in various tree species. In Japan, butt rot associated with S. himantioides is observed in Chamaecyparis pisifera and Abies sachalinensis. Previous studies have shown that S. himantioides includes five phylogenetically defined cryptic lineages, but the placement of Japanese isolates remains unclear. To clarify the phylogenetic relationship between Japanese S. himantioides and the five known lineages, we conducted a phylogenetic analysis using three newly collected Japanese isolates along with 74 S. himantioides isolates, based on the internal transcribed spacer (ITS) region, the 28 S large subunit (LSU) rDNA, the beta-tubulin (tub) gene, and the heat stress protein (hsp) gene. The concatenated phylogenetic tree showed that Japanese isolates composed a clade with a high bootstrap value distinct from the known lineages, indicating the Japanese isolates present a new cryptic lineage of S. himantioides.

During the period of seed storage in 2019, stored Fraxinus angustifolia and F. ornus seeds showed signs of infection and fungus Epicoccum nigrum was isolated from mould and necrotic lesions on the seeds. In order to confirm the pathogenicity of E. nigrum towards F. angustifolia and F. ornus seeds, an experiment that included inoculation of seeds with E. nigrum and the assessment of germinability was performed. The inoculation with E. nigrum strain caused mould to around 20% of F. angustifolia and 58% of F. ornus, necrotic lesions to 96% of F. angustifolia and 92% of F. ornus, and decrease in germinability to 95% of F. angustifolia and 97% of F. ornus seeds. This study presented, for the first time, the ability of E. nigrum to cause high infection rates and reduced germinability of the F. angustifolia and F. ornus stored seeds. The transmission routes and possibilities for preventive strategies were discussed.

During the monitoring period of alder decline phenomenon in Slovakia, indicative symptoms of Phytophthora diseases were observed in riverside stands in Slovakia. The study aimed to test the presence and diversity of Phytophthora species in declining alder stands. The samples were collected from six stands situated by rivers/streams in the central and eastern parts of Slovakia. Phytophthora plurivora and P. cactorum were detected in soil, root and water samples. The most isolated species was P. plurivora. Both Phytophthora species have been recognized in the literature as the perpetrators of black alder dieback together with other species, such as P. alni or P. polonica. To our knowledge, this is the first report of P. plurivora and P. cactorum in riverside stands with the main share of black alder in Slovakia.

The cover image is based on the Original Article Epicuticular wax content of western white pine is involved in Cronartium ribicola resistance by David Noshad et al., https://doi.org/10.1111/efp.12793